A mold system which employs interchangeable inserts for producing different molded parts is disclosed in my U.S. Pat. No. 4,828,479, issued on May 9, 1989. In that patent, I disclose a master frame which consists of an injection side and an ejection side each with its own interchangeable insert, and which, when the sections of the master frame are assembled in molding condition, produce molded pieces one at a time. The frame sides are separable along a parting line or plane for molded part removal. Each of the inserts is provided with a liquid channel and means is provided for pumping liquid through the channel from an external liquid coolant or heater source.
Obviously, when changing from one production job to another, removal of one or more of the inserts requires the liquid flow to be discontinued during replacement. More importantly, using liquid for heating has limitations, particularly when used for molding thermosetting plastic materials which require temperatures on the order of 400 to 600 degrees Fahrenheit. It is known to use electrical heater bands for heating molds, but if heater bands were employed with an interchangeable mold insert system such as that disclosed in my aforementioned '479 patent, the wiring connections to the heater bands would present a problem during replacement of inserts. The electrical connections to the bands would have to be disconnected, or if left intact, the bands would have to be separated from the inserts. Otherwise, if the bands and wires were to remain with their individual inserts, the wires would have to be "snaked" through openings in the master frame. It is avoidance of these problems which is addressed by the present invention. The solution adapts the disclosed type of molding system for electrical heating of the mold inserts and thereby provides for improved molding operations in connection with molding of thermosetting plastics.